{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-31721 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-31721 is a medium-severity vulnerability in Linux kernel, published on 1 May 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-31721 and fix it if it is affected.\n\nWhat it is: CVE-2026-31721 is a medium-severity vulnerability in Linux kernel, published on 1 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-31721 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-31721/ (Markdown: https://insights.sbomify.com/CVE-2026-31721/index.md)","id":"CVE-2026-31721","markdown":"https://insights.sbomify.com/CVE-2026-31721/index.md","name":"CVE-2026-31721","record":{"aliases":["BELL-CVE-2026-31721","DEBIAN-CVE-2026-31721","GHSA-8r63-5629-3mpc","ROOT-OS-DEBIAN-11-CVE-2026-31721","ROOT-OS-UBUNTU-2204-CVE-2026-31721","ROOT-OS-UBUNTU-2404-CVE-2026-31721","UBUNTU-CVE-2026-31721"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":true,"product_category":"Linux kernel USB gadget","requires_auth":"low_privilege","summary":"A race condition in the Linux kernel USB HID gadget driver can cause list corruption and system crashes when unbinding and rebinding the UDC while file descriptors are active.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_hid: move list and spinlock inits from bind to alloc\n\nThere was an issue when you did the following:\n- setup and bind an hid gadget\n- open /dev/hidg0\n- use the resulting fd in EPOLL_CTL_ADD\n- unbind the UDC\n- bind the UDC\n- use the fd in EPOLL_CTL_DEL\n\nWhen CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported\nwithin remove_wait_queue (via ep_remove_wait_queue). After some\ndebugging I found out that the queues, which f_hid registers via\npoll_wait were the problem. These were initialized using\ninit_waitqueue_head inside hidg_bind. So effectively, the bind function\nre-initialized the queues while there were still items in them.\n\nThe solution is to move the initialization from hidg_bind to hidg_alloc\nto extend their lifetimes to the lifetime of the function instance.\n\nAdditionally, I found many other possibly problematic init calls in the\nbind function, which I moved as well.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-08-26","github_poc":1,"max_poc_stars":0,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-08-26T16:50:40Z","kind":"github_poc","ref":"https://github.com/JakeStone594/f_hid-4.14-backports","stars":0,"title":"Backports of three published f_hid fixes (incl. CVE-2026-31721, CVE-2026-31606) to an EOL Linux 4.14.190 Android vendor kernel, with on-device verification records."}],"tier":"poc_unverified"},"has_fix":true,"headline":"usb: gadget: f_hid: move list and spinlock inits from bind to alloc","id":"CVE-2026-31721","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2026"},"n_packages":0,"n_references":8,"next":{"headline":"usb: gadget: f_rndis: Fix net_device lifecycle with device_move","id":"CVE-2026-31722"},"packages":[],"prev":{"headline":"usb: gadget: f_uac1_legacy: validate control request size","id":"CVE-2026-31720"},"products":["Linux"],"published":"2026-05-01","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A race condition in the Linux kernel USB HID gadget driver can cause list corruption and system crashes when unbinding and rebinding the UDC while file descriptors are active.","url":"https://insights.sbomify.com/CVE-2026-31721/"}